Struct datafusion_physical_expr::expressions::Max

pub struct Max { /* private fields */ }

MAX aggregate expression

Implementations

impl Max

pub fn new( expr: Arc<dyn PhysicalExpr>, name: impl Into<String>, data_type: DataType, ) -> Self

Create a new MAX aggregate function

Trait Implementations

impl AggregateExpr for Max

fn as_any(&self) -> &dyn Any

Return a reference to Any that can be used for downcasting

fn field(&self) -> Result<Field>

the field of the final result of this aggregation.

fn state_fields(&self) -> Result<Vec<Field>>

the fields that encapsulate the Accumulator’s state the number of fields here equals the number of states that the accumulator contains

fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>>

expressions that are passed to the Accumulator. Single-column aggregations such as sum return a single value, others (e.g. cov) return many.

fn create_accumulator(&self) -> Result<Box<dyn Accumulator>>

the accumulator used to accumulate values from the expressions. the accumulator expects the same number of arguments as expressions and must return states with the same description as state_fields

fn name(&self) -> &str

Human readable name such as "MIN(c2)". The default implementation returns placeholder text.

fn groups_accumulator_supported(&self) -> bool

If the aggregate expression has a specialized GroupsAccumulator implementation. If this returns true, [Self::create_groups_accumulator] will be called.

fn create_groups_accumulator(&self) -> Result<Box<dyn GroupsAccumulator>>

Return a specialized GroupsAccumulator that manages state for all groups.

fn reverse_expr(&self) -> Option<Arc<dyn AggregateExpr>>

Construct an expression that calculates the aggregate in reverse. Typically the “reverse” expression is itself (e.g. SUM, COUNT). For aggregates that do not support calculation in reverse, returns None (which is the default value).

fn create_sliding_accumulator(&self) -> Result<Box<dyn Accumulator>>

Creates accumulator implementation that supports retract

fn get_minmax_desc(&self) -> Option<(Field, bool)>

If this function is max, return (output_field, true) if the function is min, return (output_field, false) otherwise return None (the default)

fn order_bys(&self) -> Option<&[PhysicalSortExpr]>

Order by requirements for the aggregate function By default it is None (there is no requirement) Order-sensitive aggregators, such as FIRST_VALUE(x ORDER BY y) should implement this

fn order_sensitivity(&self) -> AggregateOrderSensitivity

Indicates whether aggregator can produce the correct result with any arbitrary input ordering. By default, we assume that aggregate expressions are order insensitive.

fn with_beneficial_ordering( self: Arc<Self>, _requirement_satisfied: bool, ) -> Result<Option<Arc<dyn AggregateExpr>>, DataFusionError>

Sets the indicator whether ordering requirements of the aggregator is satisfied by its input. If this is not the case, aggregators with order sensitivity AggregateOrderSensitivity::Beneficial can still produce the correct result with possibly more work internally.

fn all_expressions(&self) -> AggregatePhysicalExpressions

Returns all expressions used in the AggregateExpr. These expressions are (1)function arguments, (2) order by expressions.

fn with_new_expressions( &self, _args: Vec<Arc<dyn PhysicalExpr>>, _order_by_exprs: Vec<Arc<dyn PhysicalExpr>>, ) -> Option<Arc<dyn AggregateExpr>>

Rewrites AggregateExpr, with new expressions given. The argument should be consistent with the return value of the AggregateExpr::all_expressions method. Returns Some(Arc<dyn AggregateExpr>) if re-write is supported, otherwise returns None. TODO: This method only rewrites the PhysicalExprs and does not handle Exprs. This can cause silent bugs and should be fixed in the future (possibly with physical-to-logical conversions).

impl Clone for Max

fn clone(&self) -> Max

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Max

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq<dyn Any> for Max

fn eq(&self, other: &dyn Any) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.